Interfacial Molecular Searching Using Forager Dynamics

Monserud, Jon H.; Schwartz, Daniel K.

doi:10.1103/physrevlett.116.098303

“…Indeed, a recent experimental study found that the improvement of surface searching efficiency was even greater than that predicted by a simple intermittent hopping model, especially at long distances [47]. The results presented here provide a potential explanation for these observations.…”

Section: Prl 119 268001 (2017) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 50%

“…Moreover, even under strongly adsorbing conditions, a molecule encounters the surface many times before final readsorption. These factors may explain why the actual searching efficiency is greater than predicted by theoretical models where flights are assumed to be knowledge-free cruises, during which the molecule obtains no information about the surface [45][46][47].…”

Section: Prl 119 268001 (2017) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 93%

3D Imaging of Hopping Molecules

Barkai

¹

,

Garini

²

2017

Physics

0

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Theoretical predictions have suggested that molecular motion at interfaces-which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly-may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short-and long-range adsorbate-surface interactions. DOI: 10.1103/PhysRevLett.119.268001 Molecular transport in fluid phases is understood in terms of the Brownian motion of individual molecules and particles, and can, therefore, be predicted and controlled by parameters including the hydrodynamic radius and fluid viscosity. In contrast, the analogous behavior at the interfaces remains poorly understood despite its fundamental interest and technological relevance; i.e., the dynamics of macromolecules at solid-liquid interfaces underlie many applications including chemical sensing, catalysis, lubrication, and adhesion [1][2][3][4][5][6]. While interfacial diffusion is nominally two dimensional (2D) and conventionally described in terms of 2D Brownian motion, longstanding theoretical models [7][8][9][10][11][12][13][14][15][16] have predicted that interfacial mass transport could actually be dominated by "flights" through an adjacent liquid phase, which would dramatically alter the nature of interfacial molecular motion; an understanding of this process is necessary in order to rationally control mass transport at surfaces. Recent experimental results indirectly support these predictions by measuring the 2D projection of trajectories for atoms, molecules, polymers, and nanoparticles, in thin films, at solid-liquid interface, and on lipid bilayers, which can be represented as an intermittent process with periods of apparent immobility alternating with long flights comprising a heavy-tailed distribution [17][18][19][20][21][22][23][24][25][26]. However, the evidence for the presence of three-dimensional (3D) hops remains indirect, and critical aspects of the proposed "hopping" process remain a mystery. For example, theoretical models represent a flight as a series of hops (i.e., ...

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“…Subdiffusion, for instance, was observed for the motion of tracer particles inside living biological cells 9–15 , in artificially crowded 16–18 and structured 19–22 liquids, in pure and protein-crowded lipid bilayer systems 23–29 , as well as in groundwater systems 30 . Superdiffusion occurs in the presence of active motion, for instance, in living biological cells 31–34 or due to bulk-surface exchange 35, 36 .…”

Section: Introductionmentioning

confidence: 99%

Quantifying non-ergodicity of anomalous diffusion with higher order moments

Schwarzl

¹

,

Godec

²

,

Metzler

³

2017

Sci Rep

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Anomalous diffusion is being discovered in a fast growing number of systems. The exact nature of this anomalous diffusion provides important information on the physical laws governing the studied system. One of the central properties analysed for finite particle motion time series is the intrinsic variability of the apparent diffusivity, typically quantified by the ergodicity breaking parameter EB. Here we demonstrate that frequently EB is insufficient to provide a meaningful measure for the observed variability of the data. Instead, important additional information is provided by the higher order moments entering by the skewness and kurtosis. We analyse these quantities for three popular anomalous diffusion models. In particular, we find that even for the Gaussian fractional Brownian motion a significant skewness in the results of physical measurements occurs and needs to be taken into account. Interestingly, the kurtosis and skewness may also provide sensitive estimates of the anomalous diffusion exponent underlying the data. We also derive a new result for the EB parameter of fractional Brownian motion valid for the whole range of the anomalous diffusion parameter. Our results are important for the analysis of anomalous diffusion but also provide new insights into the theory of anomalous stochastic processes.

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“…Desorption-mediated transport has important implications for the efficiency and rate of molecular "searching", e.g. for interfacial reactive and/or binding sites [30,31,[45][46][47]. Indeed, a recent experimental study found that the improvement of surface searching efficiency was even greater than that predicted by a simple intermittent hopping model, especially at long distances [47].…”

mentioning

confidence: 99%

Three-Dimensional Tracking of Interfacial Hopping Diffusion

Wang

¹

,

Wu

²

,

Schwartz

³

2017

Self Cite

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Theoretical predictions have suggested that molecular motion at interfaces-which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly-may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short- and long-range adsorbate-surface interactions.

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Interfacial Molecular Searching Using Forager Dynamics

Cited by 23 publications

References 51 publications

3D Imaging of Hopping Molecules

3D Imaging of Hopping Molecules

Quantifying non-ergodicity of anomalous diffusion with higher order moments

Three-Dimensional Tracking of Interfacial Hopping Diffusion

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